Class PolynomialFunction


  • public class PolynomialFunction
    extends java.lang.Object
    Immutable representation of a real polynomial function with real coefficients.

    Horner's Method is used to evaluate the function.

    • Constructor Summary

      Constructors 
      Constructor Description
      PolynomialFunction​(double[] c)
      Construct a polynomial with the given coefficients.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int degree()
      Returns the degree of the polynomial.
      boolean equals​(java.lang.Object obj)
      protected static double evaluate​(double[] coefficients, double argument)
      Uses Horner's Method to evaluate the polynomial with the given coefficients at the argument.
      double[] getCoefficients()
      Returns a copy of the coefficients array.
      int hashCode()
      java.lang.String toString()
      Returns a string representation of the polynomial.
      double value​(double x)
      Compute the value of the function for the given argument.
      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait
    • Constructor Detail

      • PolynomialFunction

        public PolynomialFunction​(double[] c)
        Construct a polynomial with the given coefficients. The first element of the coefficients array is the constant term. Higher degree coefficients follow in sequence. The degree of the resulting polynomial is the index of the last non-null element of the array, or 0 if all elements are null.

        The constructor makes a copy of the input array and assigns the copy to the coefficients property.

        Parameters:
        c - Polynomial coefficients.
        Throws:
        NullArgumentException - if c is null.
        NoDataException - if c is empty.
    • Method Detail

      • value

        public double value​(double x)
        Compute the value of the function for the given argument.

        The value returned is

        coefficients[n] * x^n + ... + coefficients[1] * x + coefficients[0]

        Parameters:
        x - Argument for which the function value should be computed.
        Returns:
        the value of the polynomial at the given point.
      • degree

        public int degree()
        Returns the degree of the polynomial.
        Returns:
        the degree of the polynomial.
      • getCoefficients

        public double[] getCoefficients()
        Returns a copy of the coefficients array.

        Changes made to the returned copy will not affect the coefficients of the polynomial.

        Returns:
        a fresh copy of the coefficients array.
      • evaluate

        protected static double evaluate​(double[] coefficients,
                                         double argument)
        Uses Horner's Method to evaluate the polynomial with the given coefficients at the argument.
        Parameters:
        coefficients - Coefficients of the polynomial to evaluate.
        argument - Input value.
        Returns:
        the value of the polynomial.
        Throws:
        NoDataException - if coefficients is empty.
        NullArgumentException - if coefficients is null.
      • toString

        public java.lang.String toString()
        Returns a string representation of the polynomial.

        The representation is user oriented. Terms are displayed lowest degrees first. The multiplications signs, coefficients equals to one and null terms are not displayed (except if the polynomial is 0, in which case the 0 constant term is displayed). Addition of terms with negative coefficients are replaced by subtraction of terms with positive coefficients except for the first displayed term (i.e. we display -3 for a constant negative polynomial, but 1 - 3 x + x^2 if the negative coefficient is not the first one displayed).

        Overrides:
        toString in class java.lang.Object
        Returns:
        a string representation of the polynomial.
      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object
      • equals

        public boolean equals​(java.lang.Object obj)
        Overrides:
        equals in class java.lang.Object